Katherine (Hilary Swank) is a former minister - faith and family lost in disastrous Sudan - who has become a sort of secular exorcist at Louisiana State University, Baton Rouge. She exposes miracles as moonshine. But her big test is bayou country, a place now unhappily visited by the 10 biblical plagues of ancient Egypt (shouldn't Katrina count as the first?).

As locusts hit town, scientific Katherine starts getting her faith back. That is, she gets really scared. By then, the floating fish and bloated cattle, and the brother who looks like Satan's beef jerky after a nasty chaw, have made this the stunted, drive-in spawn of "The Exorcist" and "Deliverance."

Director Stephen Hopkins gets a point or two for Dixie-goth ambience. And Stephen Rea has a real crying game as Father Costigan, his faith so assaulted by diabolic mischief that he is virtually the plague whisperer. Hell hath no fury like a Satan offended, and poor Costigan needs no Da Vinci Code to feel the wrath.

Part of this very plagued movie's problem is that the wildly fertile new digital effects are becoming, by sheer and proficient volume, less effective. In olden days, we might look at the new ick or ugly and say, "Wow, that's creepy." Now, we just think, "Gee, nice effects."

The deeper problem, of course - the sort that can flatten even a vividly upright, credible talent like Swank - is the old "Exorcist" fallacy. The film can only imagine religion as a proposal of blind faith, a faith so pathetically blind that the only compelling "evidence" for it are the grisly works of Beelzebub (God becomes a sequel).

If you truly believe that way, you've already proven that hell exists as a lousy trick of the mind. The film has crosses, but the spirit of Christ is scarcely ever evident, except in Katherine's decent feeling for the girl.

And darn if Satan doesn't get to exploit even that, with a twist true to the corniest "gotcha" tradition of junk horror. There are times when movies feed on their pulp tradition so ravenously that nothing is left but the guilty promise of more dung to come.